I didn’t do much reading about parenting, and the stuff I did read I didn't find too helpful or insightful. I found it very much something you have to experience and figure out and no amount of prep would help. I am also way too sentimental to read books that dwell on the beauty of parent/child relationships - just want to be in the moment, you know?
In any case, I do have advice. Being a parent is f*cking hard. It's easily the hardest thing I've ever done. When my father was the age I was when I had my first daughter, I was 15 years old. Your life is not your own anymore and that can by tough at times (though worth it). My advice for first time parents is always the same - 1. Sleep when you can, especially if the baby sleeps. 2. Take help if offered (so you can sleep, decompress, etc.) - if someone offers to watch the baby, feed the baby, walk the baby, whatever - take it. 3. Don't stress about breastfeeding; do whatever it takes to make sure your child eats. We kept a feeding journal for the first week and we were feeding her every 20 minutes or so. Just wasn't working. We got a medical grade pump, stored the milk, and it not only helped us keep track of how much she was eating, we could take turns feeding her.
Good luck to your friend!